1. Field
Embodiments of the invention relate to query evaluation using ancestor information.
2. Description of the Related Art
Extensible Markup Language (XML) may be described as a flexible text format. XML is a formal recommendation from the World Wide Web Consortium (W3C). XML contains markup symbols to describe the contents of a document. In particular, XML describes the content in terms of what data is being described. Thus, an XML document may be processed as data by a program or may be stored with similar data. XML is “extensible” in that the markup symbols are self-defining. XML is a subset of the Standard Generalized Markup Language (SGML), which is a standard for how to create a document structure.
XML Path Language (XPath) is a language that describes a way to locate and process items in XML documents by using an addressing syntax based on a path through the logical structure or hierarchy of the document. That is, XPath is a language for addressing parts of an XML document.
XML Query (XQuery) provides query facilities to extract data from documents and collections. XQuery is a specification for a query language that allows a user or programmer to extract information from an XML document or any collection of data that is similar in structure to an XML document.
XQuery makes use of XPath. In XQuery, XPath expressions may be simple queries or parts of larger queries.
Notwithstanding existing techniques for processing XML queries, there is a need in the art for improved processing of XML queries.